Revisiting LiClO₄ as an electrolyte for rechargeable lithium-ion batteries

In this work, LiClO₄ was revisited and explored as a possible electrolyte in Li-ion batteries. LiClO₄ and LiPF₆ solutions in alkyl carbonate solvent mixtures were compared in several aspects: electrochemical windows with noble metal and aluminum electrodes, anodic stability, surface chemistry developed on negative electrodes (Li, Li-graphite, Li-Si), the electrochemical behavior of graphite anodes and LiMn _1/3Ni_1/3Co_1/3O₂ cathodes, and thermal behavior (solutions alone and mixtures of solutions and electrode materials). The anodic stability and the aluminum passivation are much better in LiPF₆ solutions than in LiClO₄ solutions. However, HF contamination in the former solutions worsens the passivation of negative electrodes due to reactions with surface ROCO₂Li and ROLi species. Thermal reactions of LiClO₄ produce more specific heat than LiPF ₆ solutions. However, in terms of onset temperatures for thermal runaway, the two electrolytes are equivalent. In conclusion, LiClO₄ is still an electrolyte that may be considered for use in lithium-ion batteries.